BUG: An exception occurs in the ActiveX Data Objects library when you execute a query a second time in a Visual Basic .NET application (832947)


The information in this article applies to:

  • Microsoft Visual Studio .NET (2003), Professional Edition
  • Microsoft Visual Studio .NET (2003), Enterprise Architect Edition
  • Microsoft Visual Studio .NET (2003), Enterprise Developer Edition
  • Microsoft Visual Studio .NET (2003), Academic Edition
  • Microsoft Visual Studio .NET (2002), Professional Edition
  • Microsoft Visual Studio .NET (2002), Enterprise Architect Edition
  • Microsoft Visual Studio .NET (2002), Enterprise Developer Edition
  • Microsoft Visual Studio .NET (2002), Academic Edition
Caution ADO and ADO MD have not been fully tested in a Microsoft .NET Framework environment. They may cause intermittent issues, especially in service-based applications or in multithreaded applications. The techniques that are discussed in this article should only be used as a temporary measure during migration to ADO.NET. You should only use these techniques after you have conducted complete testing to make sure that there are no compatibility issues. Any issues that are caused by using ADO or ADO MD in this manner are unsupported. For more information, see the following article in the Microsoft Knowledge Base:

840667 You receive unexpected errors when using ADO and ADO MD in a .NET Framework application

SYMPTOMS

When you execute a query from a Microsoft Visual Basic .NET application a second time, the Microsoft ActiveX Data Objects Library (ADODB) throws an exception, and you receive the following error message:
An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in microsoft.visualbasic.dll
Additional information: Syntax error or access violation

WORKAROUND

To work around this problem, use an early bound expression. To do this, locate the following code in step 6 of the "More Information" section of this article.
	cn.QueryCustomers(intDisc, rs)    '==>> exception here
    	rs.ActiveConnection = Nothing
Replace this code with the following code.
	rs = cmd.Execute(, New Object() {intDisc})

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section of this article.

MORE INFORMATION

Steps to reproduce the behavior

  1. Start Microsoft Visual Studio .NET.
  2. On the File menu, click New, and then click Project.
  3. Click Visual Basic Projects under Project Types, and then click Windows Application under Templates.
  4. In the Name box, type SampleWinApp, and then click OK.
  5. Add a Button control to the Form1.vb form.
  6. Add the following code to the OnClick event procedure of the button.
    Dim cn As ADODB.Connection
Dim rs As ADODB.Recordset
Dim cmd As ADODB.Command
Dim intDisc As Short
Dim ts As Integer

cn = New ADODB.Connection()
cn.Open("provider=sqloledb;data source=legend;initial catalog=pubs;Integrated Security=SSPI")
intDisc = 0
cmd = New ADODB.Command()
With cmd
	.Name = "QueryCustomers"
	.CommandText = "Select top 5 stor_id as CustName, Discount from discounts where discount > ?"
	.CommandType = ADODB.CommandTypeEnum.adCmdText
	.Parameters.Append(.CreateParameter("DiscountIn", ADODB.DataTypeEnum.adDouble, ADODB.ParameterDirectionEnum.adParamInput))
	.ActiveConnection = cn
	rs = New ADODB.Recordset()
	rs.CursorLocation = ADODB.CursorLocationEnum.adUseClient
	rs.LockType = ADODB.LockTypeEnum.adLockBatchOptimistic
	cn.QueryCustomers(intDisc, rs)    '==>> exception here
	rs.ActiveConnection = Nothing
	cmd.ActiveConnection = Nothing
End With
MsgBox("Successful")
  7. On the Project menu, click Add Reference.
  8. In the Add Reference dialog box, click the adodb component on the .NET tab, click Select, and then click OK.
  9. On the Debug menu, click Start to run the application.
  10. Click the button on the Form1 form. You receive a message that indicates that the code was executed successfully.
  11. Click the button a second time. The exception error message that is described in the "Symptoms" section appears.

REFERENCES

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

301075 HOW TO: Connect to a Database and Run a Command by Using ADO.NET and Visual Basic .NET

Modification Type:MajorLast Reviewed:6/15/2006
Keywords:kbvs2002sp1sweep kbMessageBox kbExceptHandling kbCOMInterop kbbug KB832947 kbAudDeveloper
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